This poem, which concerns the retirement of a well-traveled ship, borrows heavily from Ancient Greek vocabulary, and also uses Greek grammar in several sections, and makes numerous geographic references and elaborate litotic double negatives in a list-like manner. Catullus 4 has been viewed as everything from a parody of epic poetry to another piece of writing in which the Ship of State metaphor is used. The meter is iambic trimeter.

The gemelle Castoris ("twin of Castor") refers to Pollux, the other twin in the Castor and Pollux pair, who were also known as the Gemini ("twins"). The two twins were often referred to by only a single name, most commonly Castor, as though they were one, hence the tibi in line 26.